This invention relates in general to breathing devices and in particular to a new and useful gas mask having a protective hood and a respiratory gas inlet in the form of a cassette for receiving a breathing filter cartridge.
A similar gas mask with a protective hood is already known from German OS No. 32 06 484. Gas masks with protective hoods according to the invention are used as rescue equipment. For this purpose, they must be available when needed in fail-safe condition; untrained persons must be able to apply them; and these users must be able to replace breathing filters used up after protracted use.
A gas mask with protective hood has become known from German OS No. 32 06 484, U.S. Pat. No. 4,473,072, which is intended as filter equipment for escape purposes and includes a half mask. While in storage, the filter is tightly wrapped in a packaging bag for protection against environmental influences and, together with it, tied firmly up a strap in the halfmask and the protective hood enclosing it. The ends of the packaging bag are perforated by tear lines and connected to the folded protective hood so that when using the equipment, the packaging bag is opened on both sides at the same time as the protective hood is unfolded. Replacing the used-up filter by untrained persons, either to extend the time of serviceability during storage or after training exercises or while being used to prolong the equipment's usefulness is not possible because of the complicated strap fastening.
German Pat. No. 650,830 describes an oxygen mask in which a cartridge giving off oxygen and binding carbon dioxide can be replaced while using the mask. The mask has an attachment, into which a tubular container is screwed by means of a threaded nipple. The tubular container is open at both ends, and its jacket has mutually opposite openings. The one opening establishes through the threaded nipple the connection to the mask interior while the other opening leads to the exhaling tube and through it to the breathing bag. The cartridge, to be inserted from the side into the tubular container, has a jacket with openings coinciding with the openings in the container. When the cartridge is used up, it can be replaced by an insertable cartridge while the gas mask is in use. The patent describes an oxygen mask of very large, and due to its cylindrical shape, also unwieldy design in practice, however, the filter replacement idea could be adapted in an expedient manner.